This invention pertains to the formation of urethane-modified isocyanurate foams using mixtures of polyalkoxylated amines and polyalkoxylated quaternary ammonium borate esters as copolymols. More particularly this invention relates to the use of such copolymols to form foams having NCO/OH ratios of 1.5 to 3.5, using inexpensive, commercially available resin polyols. A blend of these polyalkoxylated amines and polyalkoxylated quaternary ammonium borate esters with the aforesaid resin polyol and, optionally, a polyether or polyester polyol is very stable and will remain a homogeneous liquid without phase separation and without the need for agitation for at least 3 days after blending.
Urethane and polyisocyanurate foams are manufactured using a blend of an isocyanate and a polyol. The molar ratio of isocyanate to polyol, that is, the ratio of NCO functional groups to OH functional groups, is known as the "index" or "NCO/OH ratio". Foams are manufactured with both isocyanates and polyols and when the molar ratio of isocyanate to polyol is between 1.05 to 1.15, a urethane foam is formed according to the reaction: ##STR1## The urethane moiety shown above is the repeating unit characteristic of polyurethanes, including foams. At an index between 1.5 and 3.5, a urethane-modified isocyanurate foam is formed. At indices above 4.0, an isocyanurate foam is formed having the repeating unit: ##STR2## which may have a minority of urethane linkages. Herein, the terms isocyanurate and polyisocyanurate and the terms urethane and polyurethane in reference to foams will be used interchangably.
Currently, urethane-modified polyisocyanurate foams are manufactured using polyether or polyester polyols, as for example the Voranol.RTM. group of polyols available from Dow Chemical Company, Midland, Mich. When combined with a catalyst, a surfactant, and a blowing agent, and then with an isocyanate in the known manner, these polyether or polyester polyols form a foam having good qualities. Certain resin polyols, such as the Polyol D400 resin polyol available from Dixie Chemical Company, 10701 Bay Area Boulevard, Pasadena, Tex., and the Foamol 250 resin polyol available from Jim Walter Research Corporation, 10301 9th St. North, St. Petersburg, Fla., are of a hydroxyl number sufficient so as to theoretically permit their use in foam manufacture. In practice, however, these polyols have proved to be unacceptable at concentrations in excess of 40% (wt.) of the total polyol blend for use in manufacturing high quality urethane-modified polyisocyanurate foams. Because the resin polyols are about one-third less costly than the currently used conventional polyether or polyester polyols, it is desirable that a polyol blend be found that may be used with larger quantities of such resin polyols to result in a urethane-modified polyisocyanurate foam having acceptable properties and at a lower cost.
U.S. patent application Ser. No. 476,184, filed Mar. 17, 1983, now U.S. Pat. No. 4,425,444 by the same inventor as the present invention, discloses the presently used polyol blend with other resin polyols in the manufacture of urethane-modified polyisocyanurate foams.